So, here we are; the heavy support section. After the elites section, there is no slot on the Force Organization Chart more sharply competed for, or more key to the success of a cadre. There are four choices here, and two of them are so powerful it's something of a no-brainer. It's possible to find cadres without Hammerheads, or more rarely without XV88 Broadsides, but unless someone is trying to specifically create a terrible list you literally will not see a list without one or the other. And since Hammerheads come singly and XV88s are 1-3, it's very easy to rapidly fill up the heavy support section, and therefore very difficult to squeeze anything else in. The Skyray can occasionally take the place of the Hammerhead, using its markerlights to buff the units around it and providing mobile heavy cover with its AV13 front. But the fourth choice? Oh, the fourth choice.
The Sniper Drone Team looks good enough, on paper. A 36" S6 AP3 gun is pretty good, and three of them for 80 points, with a Stealth Field for protection, isn't terrible. And you can stack three of them together in a single heavy support choice, so you can have nine of those pretty good guns scattered around the field, equipped with Target Locks so they can concentrate or spread their fire as much as you want. It sounds kind of alright, doesn't it? Unfortunately, for those upsides, there are some pretty steep downsides.
For one thing, you get three drones and a Fire Warrior with a drone controller for those 80 points, and if the Fire Warrior dies, he takes the rest of the squad with him. Given that he's T3, W1 with a 4+ save, killing him is not that difficult, so the squad is ludicrously fragile. And of course, the other three drones are just as easily dispatched. Especially since, being drones, it's extremely difficult to get them cover saves; as relatively small models, they tend to either be completely obscured or out in the open, no middle ground. Worse, for whatever reason their jet packs don't make them Relentless, so they can't manoeuvre for good firing positions or take advantage of the Tau's signature jump-shoot-jump technique, because their guns are Heavy 1. And those three fairly decent guns? They're mounted on BS3 platforms, which means these upgraded drones are arguably slightly worse at shooting than regular, BS2 twin-linked gun drones. So, three drones who can't hide, don't shoot well and are extremely fragile for 80 points, or six drones who shoot with an average skill, can JSJ and don't have to worry about losing a drone controller for 72 points; it makes the humble Gun Drone squadron look pretty solid by comparison, doesn't it? And hardly anyone takes Gun Drone squadrons!
So, what's the prescription for these guys? Well, more than any other unit, I think the Sniper Drone Team needs to be fundamentally reworked. My first suggestion would be to drop the Fire Warrior with the drone controller, perhaps replace him with a marker drone or another sniper drone, and make the remaining drones capable of fighting on regardless, but the Fire Warrior is a pretty solid piece of pewter (probably resin, now) and there's literally no chance that GW would just stop making and selling them. So, how do we make these three drones and a Fire Warrior work?
I think the key to making this unit work is the philosophy behind their Target Locks; independence. So, let's turn that up to eleven, metaphorically speaking. Under the new rubric, not only do the drones have Target Locks, they're excused from the constraints of unit cohesion entirely. They can be deployed anywhere, with no requirement that they be near each other or their controlling Fire Warrior. But the individual drones remain weak, and at 80 points for three rail rifles and a markerlight, which are ten points each whenever they show up on other units, they're still not terribly competitive. So, another small change; in place of their standard stealth field generator, let's give them O'Ralai's 'Eclipse' shield generator, from his Imperial Armour entry. This gives them a 4+ invulnerable save, and if they don't move they get the benefit of the stealth field as well. This protects them if they need to re-orient or re-position, and once they're settled they can be difficult to winkle out, which is appropriate given how much they cost. They'll still be somewhat slow and unwieldy, unless we give them Relentless too (which is a debateable move), but it makes them more survivable, and given that you can get a T4 W2 2+ XV88 Broadside for nearly the same points, survivability has to be taken into account. There's just no way for SDTs to compete if they're fragile, immobile, clustered, and one failed 4+ save away from losing the whole unit.
There are a few other, smaller tweaks worth making, too. A variable squad size wouldn't be a bad idea. Say, each SDT is 2-5 drones and a controller, and you can still field three teams for a single slot on the Force Org chart. And like all drone units, they really should be able to automatically pass break tests; these guys have a fairly good chance of fleeing as soon as they lose one drone. And giving them the Acute Senses USR makes sense, because why wouldn't you load your sniper drones with the best sensor package available? And, frankly, a bit of a price decrease wouldn't hurt, either; these things are never going to compare, point-to-point, with a Broadside. They have to go with quantity over quality, and that means they have to be cheaper. But I think, more than anything else, the ability to deploy these things anywhere you want on the board, and hide the fragile controller while you're at it, is the single most important fix that could be made to this unit.
And even then, it's still going to struggle against the two powerhouse units it shares its slot with.